In phlebotomy and other medical procedures it is oftentimes important to be able to see subsurface structures in order to better perform a surgical operation or for instance to locate veins in order to successfully complete a phlebotomy.
In the past infrared imaging in the medical environment to detect bleeding and arterial structure and for instance anything that cannot be seen in the visible region of the electromagnetic spectrum such as bone overheating, tissue overheating and the like cannot be readily observed due to the lack of the ability of instruments to provide a reasonably sharp infrared image of the inspected area.
Moreover, focal plane arrays for infrared imaging in the past have only been available with 28 micron pixel spacing which does not lend itself to anything other than a relatively fuzzy picture of the body part being inspected by the thermal imagery process.
Typically thermal imaging on the body has involved long wave infrared in the range of 8-15 μm. However with 28 micron pixel spacing image quality remains poor.
Moreover, those thermal imaging instruments that are utilized in the medical field could only focus from infinity down to 10 meters or perhaps as little as 1 meter.
However, those IR imaging systems that were capable of 1 meter focal lengths were not useful in close up viewing of the human body that require a 6 inch to 60 inch operating range. Thus, while microbolometers have been used to detect heat, the only thing that was sensed was an average heat reading over a given area. Thus, short range thermal imaging only resulted in fuzzy or blurry images. In short, these devices could not focus close in on subjects.
One of the reasons for the failure of IR imagers to have a very short focus was in part due to the size of the optics and the hardware necessary to provide a close in sharp image. It will be appreciated that providing a blotchy image of a human body part or area is not very useful in detecting subsurface structure.
Regardless of the fact that there were no single optical channel systems to produce sufficiently sharp infrared images, there was still a need for stereo imagery in certain surgical procedures to provide depth perception. Depth perception is oftentimes important because when doing surgery one can accidently for instance cut an adjacent structure so that for instance blood vessels could be nicked during the procedure. Without depth perception one could not identify the location of the internal structure. Thus in the prior art there were no stereo infrared imaging systems used, much less those capable of imaging targets within about 6 inches of the objective lenses of the binoculars. The requirement therefore is to have acceptably sharp thermal images for objects within 6 to 60 inches from the objective lenses of the binocular viewing device, a requirement not met by current infrared technology.
Referring to U.S. Pat. No. 6,701,081 a binocular system is described which enables focusing to a point in space removed from the objective lenses by skewing the optical center lines of the optical channels so that they converge on a spot somewhere short of infinity. Note that the system operates in the visible region of the electromagnetic spectrum and was not used for thermal imaging. Moreover, from this patent it appears that the minimum focus distance was on the order of 10 feet which would make it inapplicable to the type of medical imaging described above.
However, just simply having the two optical channels having optical center lines which intersect at a distance from the binoculars is not sufficient to provide crisp focusing. The only way to provide crisp focusing is by providing a focal plane array spaced from an objective lens and by moving the focal plane array relative to the objective lens.
It will be appreciated that both skewing the optical channels to intersect at a close-in range as well as providing independent focusing for each of the channels once the channels have been skewed would provide for the best resolution of a close in image.
It is noted that the above-mentioned patent uses a worm gear to rotate the optical axes of the two channels of the binoculars, and involves a relatively long focus distance incompatible with short close in work that would be required in the medical field, namely a 6 to 60 inch working distance.
Moreover, any movement of the image focal plane in the two channels of the above-mentioned patent is restricted to adjusting the image focal plane in one channel to be exactly at the same distance as the image focal plane of the other channel, there being no independent adjustment of the focal planes in each channel and certainly no automatic focus involving the movement of focal plane arrays in each of the channels relative to their own objective lenses.